That's not a problem and, instead, it's correct and is exactly as it's supposed to be.
The ones you see as empty are NOT the loaders that will do the Boarding.
Those are the empty ones that are supposed to be used for Deboarding and since GSX cannot possibly know in advance if the first command you'll use will be a Boarding or a Deboarding, it creates the gate with empty vehicles that will be used IF you start with Deboarding, but will go away if you starting with Boarding, because ANOTHER set of vehicles, which are full, will come from elsewhere to be used for Boarding.
That's simulates the fact baggage handling facilities don't have a loading place at each and every gate of the airport ( let alone on far away apron ), they would have to be filled elsewhere, and use their vehicle paths to reach the parking in use. That's exactly the same in Deboarding: they GO "somewhere" after they unload the airplane so, why should be any different on Boarding ? They come FROM "somewhere", full.
If we did as you are suggesting, it would be wrong for several reasons:
- If we started with the same loaders always empty, if you decide to start with Boarding, the empty loaders would have to be changed instantly to filled ones, and the opposite is also true, if we started with the same loaders always full, if you decide to start with Deboarding, it will automagically empty in front of you. THIS is silly and "unreal". THAT'S why they are different loaders that come and go.
- While some ultra-modern airports might have ultra-hend baggage loading facilities that connects each and every gate of the airport so that loaders won't have to do much travel, this is hardly standard and too highly dependent on the airport and, of course, it will totally wrong on Aprons, since loaders in that case WILL surely have to travel quite a bit from the passenger terminals to the parking spot.
- GSX loaders has been like this since 2012 when GSX came out, nobody ever complained about it before. The thing we ( and most user also do ) hate, is stuff "popping out" of nowhere, we try to create and destroy things out of sight, while you are proposing exactly that: create bags in front of you, which is what would happen if we used a single set of loaders that would be immediately empty or full depending on the operation. Again, THAT'S why they are different loaders that come and go.